Stock-Based Compensation Income Tax Benefits (Details) (USD $)	6 Months Ended
	Jan. 31, 2013	Jan. 31, 2012
Income Tax Benefits From Stock Based Awards [Abstract]
Actual income tax benefit recorded for the tax deductions relating to the exercise of stock-based awards	$ 79,000	$ 235,000
Less: Tax benefit initially recognized on exercised stock-based awards vesting subsequent to the adoption of accounting standards that require us to expense stock-based awards, excluding income tax shortfalls	60,000	151,000
Excess income tax benefit recorded as an increase to additional paid-in capital	19,000	84,000
Less: Tax benefit initially disclosed but not previously recognized on exercised equity-classified stock-based awards vesting prior to the adoption of accounting standards that require us to expense stock-based awards	0	2,000
Excess income tax benefit from exercised equity-classified stock-based awards reported as a cash flow from financing activities	19,000	82,000
Hypothetical tax benefits related to stock-based awards	19,846,000
Reduction to APIC and accumulated hypothetical tax benefits, due to reversal of unrealized deferred tax assets associated with certain vested equity-classified stock-based awards expiring during the period	$ 2,955,000	$ 1,186,000